Reproduction steps:
1. Open the attached ““IN-136202” project
2. Open the “Login” Scene (Scenes/GameName/Login/Login.unity)
3. Open Multiplayer Play Mode (Window → Multiplayer → Multiplayer Play Mode)
4. Tick the 'Player 2' box and wait for the Editor to load everything
5. Enter Play Mode
6. In the Game view of the Main Editor, wait for the menu to load and click the + icon in the 'Lobby List' UI then click 'Create'
7. In the 'Player 2' window press the 'Refresh' icon (circle arrow) in the 'Lobby List' UI and select the lobby (it can be behind the Play button, just click where it says 'My Lobby')
8. Wait for it to automatically start the game on both windows wait for the island to load
9. Observe the memory consumption

Actual result: Memory consumption gradually increases over time
Expected result: Memory consumption does not increase

Reproducible with: 6000.0.71f1, 6000.3.12f1, 6000.4.1f1
Couldn’t test with: 2023.1.0a3, 6000.0.1f1 (Couldn’t downgrade project because of project complexity), 6000.5.0b1, 6000.6.0a1 (Update caused lots of scripting errors)

Reproducible on: Windows 11 (by reporter), macOS 26.3.1
Not reproducible on: No other environments tested

Note: Issue is not caused by Multiplayer, but it is used to run the Scene